CONTRACEPTIVE CLINICAL TRIALS NETWORK - CORE - MALE-There is a demand for new methods of contraception that can provide effective protection against unintended pregnancy as well as reduce the risk of side effects. The mission of the CCTN is to develop protocols and conduct clinical trials that will assist in product development with the end goal to provide effective and safe contraception for men. The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) has a mission to develop safe and effective contraceptives for men who have medical conditions for which current contraceptive products are contraindicated